scholarly journals The Changing Influences of ENSO and the Pacific Meridional Mode on Mesoscale Eddies in the South China Sea

2019 ◽  
Vol 32 (3) ◽  
pp. 685-700 ◽  
Author(s):  
Pengfei Tuo ◽  
Jin-Yi Yu ◽  
Jianyu Hu
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Southern Oscillation ◽  
The South China Sea ◽  
Eddy Correlation ◽  
The South ◽  
Vector Method ◽  
China Sea ◽  
The Pacific

This study finds that the correlation between El Niño–Southern Oscillation (ENSO) and the activity of mesoscale oceanic eddies in the South China Sea (SCS) changed around 2004. The mesoscale eddy number determined from satellite altimetry observations using a geometry of the velocity vector method was significantly and negatively correlated with the Niño-3.4 index before 2004, but the correlation weakened and became insignificant afterward. Further analyses reveal that the ENSO–eddy relation is controlled by two major wind stress forcing mechanisms: one directly related to ENSO and the other indirectly related to ENSO through its subtropical precursor—the Pacific meridional modes (PMMs). Both mechanisms induce wind stress curl variations over the SCS that link ENSO to SCS eddy activities. While the direct ENSO mechanism always induces a negative ENSO–eddy correlation through the Walker circulation, the indirect mechanism is dominated by the northern PMM (nPMM), resulting in a negative ENSO–eddy correlation before 2004, and by the southern PMM (sPMM) after 2004, resulting in a positive ENSO–eddy correlation. As a result, the direct and indirect mechanisms enhance each other to produce a significant ENSO–eddy relation before 2004, but they cancel each other out, resulting in a weak ENSO–eddy relation afterward. The relative strengths of the northern and southern PMMs are the key to determining the ENSO–eddy relation and may be related to a phase change of the interdecadal Pacific oscillation.

scholarly journals Imprint of the Pacific Decadal Oscillation on the South China Sea Throughflow Variability*

2013 ◽  
Vol 26 (24) ◽  
pp. 9797-9805 ◽  
Author(s):  
Kai Yu ◽  
Tangdong Qu
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Pacific Decadal Oscillation ◽  
The South China Sea ◽  
North Equatorial Current ◽  
The South ◽  
China Sea ◽  
South China Sea Throughflow ◽  
The Pacific

Abstract Analysis of the 62-yr hindcast outputs from an eddy-resolving ocean general circulation model reveals a prominent decadal variability in the upper-layer (0–745 m) Luzon Strait transport (LST), a key component of the South China Sea throughflow. This variability is in phase with the basin-scale wind stress anomalies associated with the Pacific decadal oscillation (PDO). A composite analysis shows that during the positive phase of the PDO, the Aleutian low and its related positive wind stress curl anomalies intrude southward, reducing the trade winds and enhancing the westerly wind anomalies in the tropical North Pacific. In response, the North Equatorial Current bifurcation shifts northward, resulting in a weaker Kuroshio east of Luzon and consequently a stronger South China Sea throughflow in the upper 745 m.

Impacts of a wind stress and a buoyancy flux on the seasonal variation of mixing layer depth in the South China Sea

2013 ◽  
Vol 32 (9) ◽  
pp. 30-37 ◽  
Author(s):  
Xianjun Xiao ◽  
Dongxiao Wang ◽  
Wen Zhou ◽  
Zuqiang Zhang ◽  
Yinghao Qin ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Mixing Layer ◽  
The South China Sea ◽  
Buoyancy Flux ◽  
The South ◽  
Layer Depth ◽  
China Sea

Formation and Dynamics of a Long-Lived Eddy Train in the South China Sea: A Modeling Study

2017 ◽  
Vol 47 (11) ◽  
pp. 2793-2810 ◽  
Author(s):  
Zhongya Cai ◽  
Jianping Gan
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Northern South China Sea ◽  
Anticyclonic Eddy ◽  
The South China Sea ◽  
The South ◽  
Wind Stress Curl ◽  
China Sea ◽  
Anticyclonic Eddies

AbstractA process-oriented numerical modeling study was conducted to investigate the formation and underlying forcing of an anticyclonic eddy train observed in the northern South China Sea. Observations showed that long-lived anticyclonic eddies formed an eddy train along an eastward separated jet across the northern South China Sea in summer. The eddy train plays a critical role in regulating ocean circulation in the region. Forced by the southwesterly monsoon and prevailing dipole wind stress curl in the summer, the northward coastal jet separates from the west boundary of the South China Sea basin and overshoots northeastward into the basin. The anticyclonic recirculation of the separated jet forms the first anticyclonic eddy in the eddy train. The jet meanders downstream with a strong negative shear vorticity that forms a second and a third anticyclonic eddy along the jet’s path. These three eddies form the eddy train. These eddies weaken gradually with depth from surface, but they can extend to approximately 500 m deep. The inherent stratification in the region regulates the three-dimensional scale of the anticyclonic eddies and constrains their intensity vertical extension by weakening the geostrophic balance within these eddies. Analyses of the vorticity balance indicate that the eddy train’s negative vorticity originates from the beta effect of northward western boundary current and from the subsequent downstream vorticity advection in the jet. The jet separation is a necessary condition for the formation of the eddy train, and the enhanced stratification, increased summer wind stress, and associated negative wind stress curl are favorable conditions for the formation of the anticyclonic eddies.

scholarly journals Interannual 14C Variations During 1977–1998 Recorded in Coral from Daya Bay, South China Sea

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 595-601 ◽  
Author(s):  
C D Shen ◽  
W X Yi ◽  
K F Yu ◽  
Y M Sun ◽  
Y Yang ◽  
...  
Keyword(s):  
South China Sea ◽  
Correlation Coefficient ◽  
South China ◽  
Interannual Variation ◽  
Southern Oscillation ◽  
Thermal Structure ◽  
The South China Sea ◽  
Daya Bay ◽  
The South ◽  
China Sea

Twenty-two annually banded samples of coral from 1977 to 1998 were collected from Daya Bay, South China Sea, and bomb 14C concentrations were determined. The interannual variation of coral Δ14C is controlled mainly by oceanic factors. In ENSO years, the coastwise upwelling current of the South China Sea has been intensified; hence, the coral Δ14C displays its minimum value. The interannual variation curve of Δ14C in coral bears a relationship with the Southern Oscillation Index (SOI) curves: the correlation coefficient between Δ14C and (SOI)w is 0.43 and the correlation coefficient between Δ14C and (SOI)y is 0.27. The coral Δ14C has no remarkable response to the variation of solar radiation energy. In the past 20 yr or so, the general situation and oceanic thermal structure of the South China Sea are still stable even though interannual variations in atmosphere-sea interaction and upwelling current driven by the tropical energy have occurred.

An overview of 10-year observation of the South China Sea branch of the Pacific to Indian Ocean throughflow at the Karimata Strait

2019 ◽  
Vol 38 (4) ◽  
pp. 1-11 ◽  
Author(s):  
Zexun Wei ◽  
Shujiang Li ◽  
R. Dwi Susanto ◽  
Yonggang Wang ◽  
Bin Fan ◽  
...  
Keyword(s):  
Indian Ocean ◽  
South China Sea ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
The Pacific ◽  
Karimata Strait

Coral δ18O records as an indicator of winter monsoon intensity in the South China Sea

2003 ◽  
Vol 59 (3) ◽  
pp. 285-292 ◽  
Author(s):  
Zicheng Peng ◽  
Tegu Chen ◽  
Baofu Nie ◽  
M. John Head ◽  
Xuexian He ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Southern Oscillation ◽  
Winter Monsoon ◽  
The South China Sea ◽  
The South ◽  
Porites Lutea ◽  
China Sea ◽  
Meteorological Observatory ◽  
Monsoon Intensity

AbstractWe have used correlative analysis between mean December–January–February winter wind velocities, measured at the Xisha Meteorological Observatory (16°50′N, 112°20′E) in the middle of the South China Sea, and mean δ18O data for the corresponding month from Porites lutea coral, collected in Longwan waters (19°20′N, 110°39′E), to obtain a linear equation relating the two datasets. This winter wind velocity for the South China Sea (WMIIscs) can then be correlated to the coral δ18O by the equation WMIIscs = −1.213–1.351 δ18O (‰ PDB), r = −0.60, n = 40, P = 0.01. From this, the calculated WMIIscs-δ18O series from 1944 to 1997 tends to decrease during the 1940s to the 1960s; it increases slightly during the 1970s and then decreases again in the 1980s and 1990s. The calculated decadal mean WMIIscs-δ18O series had a obvious decrease from 5.92 to 4.63 m/s during the period of 1944–1997. The calculated yearly mean WMIIscs-δ18O value is 5.58 m/s from 1944 to 1976 and this decreases to 4.85 m/s from 1977 to 1998. That is the opposite trend to the observed yearly mean SST variation. The yearly mean SST anomaly is −0.27° from 1943 to 1976 and this increases to +0.16° from 1977 to 1998. Spectral analysis used on a 54-year-long calculated WMIIscs-δ18O series produces spectral peaks at 2.4–7 yr, which can be closely correlated with the quasibiennial oscillation band (QBO band, 2–2.4 yr) and the El Ñino southern oscillation band (ENSO band, 3–8 yr). Hence most of the variability of the winter monsoon intensity in the middle of the South China Sea is mainly constrained by changes in the thermal difference between the land and the adjoining sea area, perhaps due to global warming.

scholarly journals A study of El Niño-Southern oscillation impacts to the South China Sea region using ground-based GPS receiver

2013 ◽  
Vol 423 ◽  
pp. 012043 ◽  
Author(s):  
Wayan Suparta ◽  
Ahmad Iskandar ◽  
Mandeep Singh Jit Singh ◽  
Mohd Alauddin Mohd Ali ◽  
Baharudin Yatim ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
The South China Sea ◽  
El Nino Southern Oscillation ◽  
Gps Receiver ◽  
The South ◽  
China Sea
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